help pulsing light

the duster did not want to start no spark this has been an on & off problem work's great then it won't start so with the snow blowing out side I turned the tone's on grabbed a pop & started to go over each connection it has electronic ignition there is a block by the dist. that wire's from the dist connect into after I cleaned the block I tested the connection's with the key in the on position to see which had power I have one that pulsates like the single light was on just on & off can anyone tell why or what this would be or what it's for thank's